Abstract
The introduction of the hemorrhagic principle, Dicoumarol, (3,3′ methylenebis (4-hydroxycoumarin)) has supplied a new impetus to the study of the prothrombin mechanism of plasma. Several investigators 1 2 3 4 have suggested that dilute plasma may be a more sensitive indicator of variations in prothrombin activity and consequently may be more efficaciously used to follow Dicoumarol therapy. During the course of this investigation on prothrombin activity of serial dilutions of human plasma, data have been obtained which suggest a physiological basis for clinical conditions manifesting an intravascular disturbance of the coagulation mechanism. Quick's one stage method applied to dilute plasma showed a difference in coagulation activity of “normal” plasma and plasma obtained from individuals having intravascular disturbances.
Prothrombin activity curves for “normal” plasma and plasma obtained from individuals in various clinical conditions were constructed by serial dilution with physiological saline. Quick's 5 method was followed meticulously in every detail. The clotting time for oxalated undiluted plasma (12-15 seconds) was repeatedly corroborated with regard to the narrow limits of variation that occur and found to be in Complete agreement with the above mentioned investigator. However, with 12.5% and 25% plasma the clotting time deviated markedly from the values reported by Quick, indicating less prothrombin activity for these dilutions. Reproducible activity curves have been obtained from 60 “normal” individuals by the present method. Fig. 1 shows the limits of variation for “normal” human plasma for all dilutions compared with Quick's published data. It is to be noted that the greatest difference was encountered when 12.5% plasma was used. The factors responsible for the difference found are being subjected to a critical study.
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